1. Field of the Invention
This invention relates to keyboard instruments such as upright pianos having loudness increase structures.
2. Description of the Related Art
In general, upright pianos are constructed to realize opening functions of top covers which are hinged to top places of cases, so users or players are capable of opening the top covers to increase tone volumes of piano sounds. However, because general users tend to place some articles or objects on the top covers, the upright pianos cannot always demonstrate the opening functions for increasing tone volumes of piano sounds.
It is an object of the invention to provide a keyboard instrument such as an upright piano that is capable of realizing an opening function for increasing tone volume of piano sound without being interrupted by an article or object being placed on a top cover.
A keyboard instrument such as an upright piano is basically constructed by a keyboard, an action, a case assembly, a fall assembly, a back hollow assembly and a top door assembly. Herein, the fall assembly provides a fall cover for covering the keyboard, and the top door assembly having an opening top door is linked to the fall assembly by way of the back hollow assembly. The top door pivotally moves in response to movement of the fall cover of the fall assembly being closed or opened, wherein when the fall cover is opened, the top door opens to produce a small gap (52) in proximity to a lower end of the top door. The small gap allows piano sound to be partially released from a casing to increase loudness of the piano sound and to enhance clarity in tone color of the piano sound. Because the keyboard instrument arranges the top door not to be interrupted by an article or object being placed on a top board by a user or player, it is possible to secure the opening function of the top door being opened in connection with opening of the fall cover, so the keyboard instrument is capable of normally demonstrating a loudness enhancement effect of sound.
In addition, the keyboard instrument further provides a damping mechanism for imparting resistance load to the fall cover being closed or opened. That is, the damping mechanism uses a rotation damper containing viscous fluid that moves in response to pivotal movement of the fall cover to produce torque by which an increasing load is to be automatically imparted to the fall cover being closed. Thus, it is possible to avoid occurrence of accident due to slammed shut of the fall cover of the piano.